Sunday, February 24, 2013

 

How Uncle Rod Almost Became a Dob Guy


Well, I am a Dobsonian guy, sort of. I’ve got enough of the suckers, muchachos: a 12.5-inch, an 8-inch, a 6-inch, and even a little 4.5-inch, Yoda, my StarBlast. I own and use the big, friendly alt-azimuth telescopes, but I’ve always been more identified with Schmidt Cassegrains and other Schmidt designs like the Maksutov. It hasn’t always been that way though; I almost gave up CATs for Dobs one time.

When did I first hear about Dobsonian mounted telescopes? I just can’t remember, but it must have been in the early 1980s, about the time small mentions of this different sort of Newtonian reflector began to appear in Sky and Telescope and Astronomy. Yeah, I know the old Telescope Making magazine was running articles on Dobsonians by 1979 and even calling the telescopes that,  but Unk has always been more of an amateur telescope buyer than maker, and confined his reading outside S&T and Astronomy to Deep Sky (when it went big time in ’82).

But, yeah, by the early 80s, I knew some amateurs were doing what sounded preposterous:  making telescopes not from aluminum and fiberglass and steel and brass, but from wood and cardboard. The ultra thin mirrors in the scopes they were building also flew in the face of convention. A mirror, this bunch of wild-eyed revolutionaries claimed, didn’t have to have a diameter to thickness ratio of 6:1. It could be way thinner if it were properly supported, maybe by a fabric sling. Hell, you could even make yourself a nice big mirror out of surplus porthole glass. Not only were folks apparently making these things in droves out on the west coast, a company of some repute at the time, Coulter Optical, was selling ‘em, running ads in the magazines every cotton-picking month.

All of which sounded like heresy to young Rod. No lathes and machining? Cardboard for a tube—like the dadgum Criterion Dynamax SCT we were still laughing about? Wooden alt-azimuth mount? How the hell would you TRACK THE STARS? And wouldn’t it be super shaky? Enormous mirrors sitting in some kind of little hammock instead of a real mirror cell? Sounded like you’d have yourself a right fine shaving mirror, not a telescope mirror. That’s what Unk and most of his bubbas thought, anyway.

It took me till the early 1990s to get beyond just reading about Dobsonians and get up close and personal with them. The impetus was the need to finance a divorce, which impelled me to sell my Celestron Super C8 Plus (it was not a world-beater optically, anyway). What to do? Well, I’d start saving for an SCT. Maybe one of them new fangled LX200s or a nice Powerstar C8, but I needed something better than my single remaining scope, the good, old Pal Junior, right away.

In the interest of saving as much moola as possible, I’d do what I’d done back in the late 60s and early 70s, homebrew a 6-inch Newtonian. Only this time I’d buy a primary mirror from somebody. Given the demands of my job, I didn’t feel like spending weeks with a pitch lap. How about a tube? The more I thought about it, the more I began to think the Dobbie gang had a pretty good idea with their Sonotube concrete form telescope tubes. I was willing to give that a try, anyhow. As for the mount, I’d hop on down to Home Depot, pick up some pipes and valve grinding compound, and do yet another pipe mount. Maybe. The things worked, as I knew from my days as a boy ATM, but they sure were heavy.

What pushed me over the edge into Dobdom was an excellent book, Richard Berry’s classic Build Your Own Telescope, which I’d bought from the old Astronomy Book Club not long before. I wasn’t much interested in building scopes at the time, but the ABC didn’t always have much in the way of amateur astronomy books, and when they had one, like Berry’s, I jumped on it.

While Richard’s book included plans for a very nice pipe/wooden equatorial, it appeared beyond my modest wood-working capabilities. Also in his book, however, was a simple but attractive 6-inch Dobsonian that, the more I thought about it, seemed just the thing. Light. Easy to build with no thread lapping with that nasty valve grinding compound. All I’d need was plywood, some Teflon pieces, and a few odds and ends.

According to Mr. B., I wouldn’t be giving up anything other than equatorial movements if I went Dob. The mount’s motions would be smoother and stability better than those of my old Pipe rigs, which I’d thought purty good. And I could enter the Dobbie club for the price of a sheet of particle board. In the interest of saving even more money I eschewed plywood; I didn’t expect this to work to my satisfaction, and wanted to spend as little as possible on it.

Turned out there were only two difficult things about the project:  getting the parts and (as usual for Rod) following the instructions. The primary mirror, an f/8 from Parks, arrived without too much delay, but the everything else, the focuser, secondary, spider, and primary mount, which I ordered from the prime ATM parts merchant of the day, Kenneth Novak, took forever.

When my shipment from the dude we referred to as “Old Man Novak” finally came, it was missing a couple of items. I finally got the vital one, the secondary holder, but I never did receive the copy of his (highly regarded at the time) book, Newtonian Notes, I paid for. With the addition of a few pieces of Teflon I found locally and a length of Sonotube from a building supply house (you should have seen the expressions on those good old boys’ faces  when I told 'em I was going to make a telescope out of it) I was ready to go.

I painted the Sonotube a nice glossy white outside and flat black inside, and drilled the requisite holes for focuser and primary mirror mount. I did forego the plywood end rings Richard’s pretty six-inch featured. I tried making one, but hand tools and a piece of cast off and somewhat water-logged ¼-inch plywood did not spell “success.” The Sonotube was more than strong enough to support itself and the rings would be entirely cosmetic, anyway.

The mount was no problem. The rocker box and ground board went together in a hurry. Building them with particle board made them heavier than they would otherwise have been, but the result was manageable in a size appropriate for a six, and was still lighter than my old pipe mounts had been. Made a box for the tube to slide into, put toilet floor flanges on its sides for bearings, mounted the Teflon squares on the rocker box and ground board and I was done.

Result? Disappointing as hell. Why, this thing was way shakier than my pipe mounts. So, all that talk about vibration absorbing wood and cardboard had been nothing but malarkey? Not really. As usual, I had failed to read the instructions carefully: I shoulda used three Teflon pads on the ground-board, not four. Three resulted in tripod-like steadiness; four a see-saw effect. I redid the azimuth bearings and was good to go. The mount was now amazingly smooth and steady. No, there was no motorized tracking, but I soon found I didn’t miss it a bit for visual use, and that the Dobbie Shuffle, nudge-nudge-nudge, was soon second nature even at high power.

Yes, it was just a 6-inch, and was frankly a little ugly, but I used that humble first Dob to great effect for about a year. The mirror was fairly good, if not as excellent as I’d hoped it would be given the hype and hyperbole about Parks’ optics on that pre-Internet online venue, Fidonet Astronomy. It was noticeably poorer than the last homebrew 6-inch mirror I’d done (and which I had foolishly sold), but it was Good Enough and initiated me into the joys of Dobbies. Equatorial-Schmeckquatorial; it was nice to point and shoot with the aid of a Telrad and not have to worry about dadgum RA and declination locks. I guess I was a convert.

I can’t eat just one Lays’ potato chip, and I couldn’t stop with just one Dobsonian. One evening after work I was browsing the pages of the then-current Sky and Telescope when my eyes lit on Coulter Optical’s latest ad. Something had changed, and what had changed was the addition of a second 8-incher, an f/7, as an alternative to their 8-inch f/4.5 telescope. The price? Fracking unbelieveable: $239.50 for the Dob complete with an eyepiece (but no finder). As I have said before, I simply could not resist, and ordered one.

Given Coulter’s reputation for slow delivery—they quoted me two YEARS for a 10-inch f/6 primary one time—I didn’t expect to see the f/7 for a long while. I ordered it more on a lark, because I could, than anything else. I was gobsmacked when it showed up at the front door a mere two weeks after I sent off my check. And, even more amazing, it was semi-clear for first-light night.

How did she do? “Mabel,” as I came to call her, did alright. The Moon looked good, if not blow you away good, despite her supposedly forgiving slow focal ratio. The mirror was not perfect, the star test revealing some turned down edge. Not a crazy amount, though. Jupiter looked cool and the Moon was wonderful. I even shot a prize-winning image of a Moon - Saturn occultation a few years later by holding a video camcorder up to her eyepiece.

Nevertheless, I didn’t start thinking about a serious Dob till April of 1993. Everybody knows what the brightest supernova of the last century was, of course, SN1987a in the Large Magellanic Cloud. But that was way down south and invisible to us losers in the Northern Hemisphere. The best we’d seen in a long time was SN 1993J, which burst into life in Bode’s Galaxy, Messier 81, and was discovered on March 28 of ’93. The maximum brightness of what later turned out to be a Type Ib was 10.5, not close to the brilliance of the Southern Hemisphere’s relatively nearby 1987a, but still visible with modest optical aid from fairly poor sites.

Like the frontyard of Mama’s house, Unk’s boyhood home, where Miss Mabel and I set up to get a good look at the Northern sky. One thing ol’ Unk had to admit was that a Dob is considerably more maneuverable than an equatorial as you move farther north (the zenith is another matter). Anyhoo, even in the light pollution with a fracking mercury vapor light five meters away, it was the work of just a few minutes with the Telrad to get M81 in the field of my 25mm Ortho.

Given the condition of the skies, which seemed at least twice as bad they’d been in the late 1960s—and they weren’t that great back then—I didn’t expect to see much/anything. And yet…and yet…there is was, standing out like a sore thumb. Wow! An extragalactic supernova with my 239 buck special. And it had taken all of five minutes to set the scope up and not even that long to get M81 in her field. Did I really want an SCT, after all?

Those doubts were only enhanced by my second look at the supernova. My friend Pat Rochford, who I’d met shortly after my return to The Swamp not long before, was possessed of a big mother of a Dobsonian. An 18-inch Sky Designs by Bob Combs.

For those of you who don’t remember them, Bob’s telescopes were in the first generation of commercial/custom truss tube Dobsonians. They were heavy compared to today’s truss tube scopes, but since they could be broken down they were much more pleasant to lug around than the big Sonotube monsters. The Sky Designs scopes were also a little crude by today’s standards, with the secondary assembly, for example, being made of wood. But they were good telescopes, revolutionary for the time, really, and I could only imagine what 18-inches of horsepower would do for M81.

I got my chance to find out a few days after my initial look at the supernova, when Pat hauled his big Dob—which would be replaced by an even bigger one in just a couple of years—out to the public schools’ Environmental Studies Center where the good old Possum Swamp Astronomical Society held and still holds its meetings. Not only was the supernova even more obvious in Pat’s big gun, if I held my mouth just right I thought I could see a hint of one of M81’s gossamer arms in the light pollution.

I also couldn’t help but notice the relative ease with which Pat unloaded an 18-inch from his Isuzu Trooper. And how quickly it was ready to go. This was an 18-inch telescope, for god’s sake, and it was obviously much easier to manage than a C14, which I’d previously thought was the most portable big mutha. I couldn’t deny the smoothness of the scope’s motions, either, or the fact that Pat didn’t need batteries or AC power. Was a Big Dob in my future? Maybe. Maybe at least a medium-big one over the the short run.

The view I had of M81 in Pat’s 18-inch wasn’t all that was pushing me ever more into the Dobsonian camp; I had the chance to try another bigun in the few hours of clear sky we were granted at the 1993 Deep South Regional Star Gaze. I was treated to a view of M13 that is still locked in my memory. What was amazing was the plebian pedigree of the scope I saw it with. It was Coulter’s 17.5-inch Odyssey II. The name was kinda cool, but the scope itself was just as plain and simple as can be imagined:  A water heater sized Sonotube and a roughly figured mirror.

But it was a big mirror, almost 18-inches, and the dude who gave me a look through his much-loved telescope was using a brace of TeleVue Nagler 82-degree apparent field eyepieces. Admiring the Great Cluster in that expansive field led to an epiphany of sorts. A Dobsonian didn’t have to be expensive to show you incredible deep sky wonders. Maybe even the still financially depressed Unk—divorce lawyers like to be paid, and I had paid a couple of ‘em—could manage a sorta-big one.

I was tempted to get on the horn and tell Coulter to get an Odyssey II, or at least the Odyssey I 13.1-inch, on its way to me ASAP, and not worry about how long that might take. That’s just what I would have done if an issue of Sky and Telescope hadn’t hit the mailbox just before Christmas
.
Thumbing the magazine in my usual slow fashion, it took me a while to get to the big Meade ad spectacular splashed across a couple of pages toward the back, but when I did I was surprised. In them days, Meade was riding high with the LX200 and I was not surprised they were introducing some new products around Christmas. I was surprised at what they were introducing: Dobsonians. Pretty Dobsonians.

Actually, they didn’t look that different from the Coulters: big Sonotube tubes with smallish side-bearings sitting in rocker boxes. But they did have a more professional look. The Sonotubes were nicely finished in white with fancy Meade stickers, the focusers were real rack and pinion jobs instead of the Odysseys’ assemblage of plumbing parts, a genuine 25mm eyepiece was standard (the Coulters came with a surplus binocular eyepiece), and a finder—always optional with Odysseys—was also included in the package.

I was impressed, and brought the magazine to our annual club holiday dinner in January of 1994 to get Pat’s opinion. Back then, these holiday outings were distinctly déclassé affairs. The PSAS inevitably wound up at America’s Family Restaurant, the now (nearly) gone Shoney’s, where we mobbed their extensive salad/hot-bar. Not much like our upscale Christmas parties at the famous Ed’s Seafood these days. I didn’t care pea turkey. Munching Shoney’s fried chicken wings was OK, but what I was really after was my friend’s blessing for what I was about to do: order a big Dobsonian.

Pat was almost as impressed as I was by the Meade ad and kinda blown away that a major manufacturer was getting into the Dobbie business. The only question, which he posed to me, was “How big?” I had been ruminating on that and thought I had the answer. The StarFinders, as Meade called their Dobs, were available all the way from 6 to 16-inches. I had a 6 and I had an 8. A 10-inch would be wonderfully portable, but Pat concurred with my assessment that it wouldn’t be a huge increase in horsepower over my 8-inch. The 16-inch? The very idea of carrying a hot-water-heater Dob around in my Hyundai Excel was ludicrous. As Miss Goldilocks might say, “The 12-inch was just right.”

I’ve told y’all the story of the 12-inch StarFinder’s arrival at Chaos Manor South more than once. So here I will just say the telescope who’d eventually come to be known to all and sundry as “Old Betsy” mostly lived up to my expectations. Her optics were outstanding. The 50mm finder was good, the extra eyepieces that came in the upgrade package I ordered were horrible, and the smoothness of the mount’s motions was acceptable but needed fine tuning. Oh, and the 1.25-inch focuser that had looked so nice in the ads turned out to have a base made of plastic. Nevertheless, it worked well.

The 1994 Deep South Regional Star Gaze, Miss Dorothy’s first star party, was a triumph for Betsy. When there was the occasional clearing, she showed us the deep sky in detail. I was mucho impressed; her images were better than I dreamed—and I’d done considerable dreaming about my 12-inch during the long wait for her arrival—and I’d been able to stuff the pea-picking thing in my Hyundai. Today, numerous fork and GEM mount SCTs down the line, Miss Dorothy still laughs about how Unk RAVED about Dobsonians in them days, casting heaps of scorn on equatorials and even Schmidt Cassegrains. So, the die was cast. After Betsy I’d be on to Sky Designs or maybe those new guys, Obsession?

Nope. In truth, by the time Betsy arrived, six months after I ordered her, my Dobsonian fever had already begun to cool. That cooling actually began with the total Lunar eclipse of November 1993. Lunar eclipses can be fun to view, especially with binoculars, but I wanted more. I wanted to document the event in photos. Using the same primitive “system” I’d used nearly thirty years before with my 3-inch Tasco, I put my SLR on a tripod, set that beside the scope and shot into the eyepiece afocally. And had a ball. Way more fun than I’d a-had just running outside with binoculars during the commercial breaks in Married with Children.

Course, to get prints of the pictures I’d shot on Tri-X black and white film, I’d have to set up a darkroom again. Soon, I was once more immersed in the arcana of Dektol and D76 and big honking Bessler enlargers. I’d been doing strictly visual observing ever since Comet Halley (who I tried to photograph a time or two) had departed, and I was ready for a change. That change, it appeared, would be astrophotography. This would be my third or fourth flirtation with the Difficult Art, and I was determined to get it right this time.

Getting it right would require the proper equipment, and that equipment was not an undriven Dob, even a fancy one. I needed, yep, a good old C8. Before long I was pouring over catalogs and back issues of Sky and Telescope searching for the perfect SCT, which turned out to be the one me and my buddies considered an astrophotography powerhouse back then, the Ultima 8. My timing was, for once, good. By the time I’d learned the ropes of astro-imaging the modern way with off-axis guiders and PEC and Tech Pan 2415 and the new Fuji color films, the one - two - punch comets, Hale-Bopp and Hyakutake, were on their way in.

Photography aside, I was reeducated about what a wonderful visual scope a C8 is. No standing, no nudging along. Sit in perfect comfort and stare at your quarry at high power. The Ultima had excellent optics, and made planetary observing, which I was heavy into in them days, a joy.

I’ve continued to love and use Old Betsy, even upgrading her a time or three. But I’ve never advanced to a bigger or fancier Dobsonian. I’ve done far more imaging than visual looking these last eight – ten years, especially, and there always seems to be some new camera or imaging accessory or software that sucks up the time and money that might otherwise be earmarked for an Obsession Ultra Compact.

And that is OK, muchachos. I do sometimes think wistfully about my two or three years with big, gawky telescopes, sketchbook in hand. If I hadn’t spent that time with my Dobsonians, The Urban Astronomer’s Guide might never been written. But even astro-dilettante Unk eventually found his particular place in this greatest and broadest of all hobbies. It took me a while to realize it, but my fated spot is in the field with an SCT and a computer, viewing the output of my ST2000 CCD, my DSLR, or my Mallincam Xtreme, not at the top of a ladder next to a 25-inch Dobbie. No matter how exciting or romantic that sometimes sounds on the darkest of nights.

Next Time:  My Favorite Star Parties:  Deep South Regional Star Gaze 1993...


Comments:
Great article. I'm returning to astronomy after a fifty year break for work, family, life. I see that a couple things have changed! Thoroughly enjoy your blog and reviews, comments on CN, and articles in S&T.
Thanks, Pete
 
Great article. I'm returning to astronomy after a fifty year plus break for work, family, life. I see a few things have changed! Thoroughly enjoy your blog, reviews and comments on CN and S&T articles.
Thanks, Pete
 
The Dobsonian no doubt was an influential design of the alt-az Newtonian, but the name is almost universally misused these days. The scopes on the Telescope Making cover and on the Odyssey ad in your post are Dobsonians, the other scopes are not. The design is hardly ever seen these days; instead seemingly any alt-az Newtonian is called a Dobsonian for no reason, and I meet amateurs who think John Dobson invented mounting a Newtonian alt-az!
 
It doesn't really matter who invented what at this late date. An alt-az telescope using Teflon bearings and formica (or similar materials) is known as a Dobsonian now, and will continue to be. ;-)
 
Unk ROd, great insights on our obscure hobby/passion. When I got back into observational astronomy in 1998, I chose a Meade LX50 due to its low relative cost vs. and LX200. I considered motorized tracking was essential to me as I wanted to do astrophotography. So after the struggles of getting through the learning curve on polar alignment, it was a pleasure to use this instrument.
A friend of mine had a dob and it always impressed me how FAST you can set one up vs an SCT, which is great in a public astronomy outreach venue. WIth a dob you do not have a client waiting in line with his arms folded and tapping his feet, who asks you "When are you going to be ready with your telescope, bub?". This actually happened to me in 1999 at a pubilc star party at Mt Wilson Observatory.

 
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